The concrete evidence of flexistyly in Plagiostachys: pollination biology of a wild ginger on Hainan Island, China

Abstract

Flexistyly in Plagiostachys was first reported by Takano et al., while they provided no detailed study on pollination biology and breeding system. In this study, we tested this suspicion in one species of Plagiostachys (Plagiostachys austrosinensis). Field observations suggested that flexistyly was present in this species, and stigmatic behavior was similar to that reported for Alpinia and Amomum species. Two phenotypes (anaflexistylous and cataflexistylous) occurred in a ratio of 1:1 in natural populations. Anthesis began around 1530–1600 h and lasted for about 24 h. Pollen viability and stigma receptivity remained high throughout the flowering process. Mean nectar volume (4.15–11.30 μL) and mean sugar concentration (>32%) also remained at a high level during the flowering process. No fruit set occurred in unpollinated bagged plants. Two pollinators (Bombus pyrosoma and Vespidae spp.) and one pollen robber (Mutillidae spp.) were found as flower visitors. Fruit set following self‐pollination and cross‐pollination did not differ significantly in the cataflexistylous morph. Partial self‐incompatibility was apparent in the anaflexistylous morph. These results provide the concrete evidence of flexistyly in Plagiostachys and a more thorough understanding of its evolutionary origin in gingers.

A Draft Genome of the Ginger Species Alpinia nigra and New Insights into the Genetic Basis of Flexistyly

“…Flexistyly is a complex phenotype, and we thus hypothesised it may be controlled by multiple genes (as is, for instance, distyly). These genes are presumably tightly linked as the morph types are always found in a 1:1 ratio within a population [ 16 , 17 , 18 , 21 , 23 , 68 ]. These loci would be expected to reside in a region of reduced recombination and inherited together, such as a large polymorphic chromosomal inversion or a supergene [ 9 , 69 , 70 ].…”

“…It is also found in several other ginger genera such as Amomum s.l. , Etlingera , Paramomum , Plagiostachys and Siliquamomum [ 21 , 22 , 23 , 24 , 25 ]. The two stylar morphs are always present in a 1:1 ratio in natural populations and hence it is presumed that two alleles segregating at a single locus control flexistyly [ 19 ].…”

Simultaneous movement of style and stamen set during anthesis in Etlingera elatior (Zingiberaceae)

“…This floral system was described in Alpinia blepharocalyx, in which Zhang et al (2003) observed two floral morphs, the cataflexistylous, in which the receptive stigma remains erect above the dehiscent anther in the morning and curves over the indehiscent anther in the afternoon, and the anaflexistylous, where the receptive stigma bends over the indehiscent anther in the morning and becomes erect, in a superior reflex position in the afternoon, when the anther begins to release pollen. This mechanism has been documented in 24 Zingiberaceae species (Cui et al 1996;Li et al 2001;Zhang et al 2003;Jia et al 2015), including the genus Etlingera (E. yunnanensis). However, Cui et al (1996) did not characterize in detail flexistyly in E. yunnanensis.…”

“…Some inflorescences are partially subterranean, for example in E. megalocheilos. Territorial spider-hunter birds (Arachnothera longirostra) and long-tongued bees have been reported as pollinators of Etlingera species (Poulsen 2006;Jia et al 2015).…”